This invention relates to a method of forming a spacer used to separate end to end piping which are to be welded together.
A problem prevalent in welding is maintaining the separation of a pipe and the internal shoulder of the fitting to which the pipe is to be welded. The spacer of this invention is of similar construction and function of that spacer in U.S. Pat. No. 4,346,918 granted Aug. 31, 1982. Many industries that utilize the spacer require it to pass a stress corrosion cracking resistance test. This ASTM. G36-87 test involves immersing the spacer in a 42% boiling magnesium chloride solution that accelerates destructive forces to simulate long term usage of the spacer. On all previous occasions when this test has been conducted on a spacer in which all the protrusions were formed at one time, hairline cracks were noticed at the base of the center protrusion after seven days of exposure to the solution, definite evidence of cracking at the base of the center protrusion was noticed after fourteen days of exposure and the spacer actually broke at the base of the center protrusion after twenty-one days of exposure.
To alleviate this stress inherent in the spacer due to cold forming, the present method forms the rear or center protrusion of the spacer first allowing stresses from this rear hump to escape or be relieved through the split in the ring. Then, the remaining protrusions of the spacer are formed. This minimizes the compressive stress within the spacer between protrusions. For example, when the test utilizing the magnesium chloride solution is performed on this spacer, no evidence of discoloration, cracking, or deterioration of the rings was revealed after twenty-eight days of exposure to the solution.